1. Field of the Invention
The present invention relates to a compound scanning probe microscope having functions of both an optical microscope which obtains an optical observation image of a sample through an objective lens and a scanning probe microscope which obtains a scanning probe observation image by scanning a cantilever over the sample.
2. Description of the Related Art
Conventionally, there are optical microscopes which can be easy to optically observe a sample having a micro size (hereinafter referred to as micro sample). Recently, in the observation of the micro sample, the scanning probe microscope (hereinafter referred to as SPM) which can observe the micro sample with resolution higher than that of the optical microscope is frequently used instead of the optical microscope.
There are compound microscopes having functions of the optical microscope and SPM. For example, Jpn. Pat. Appln. KOKAI Publication No. 8-226928 and Japanese Patent No. 2824463 disclose such the compound microscopes in which both the objective lens and a small-size SPM are attached to a revolver provided in a microscope main body. The optical observation with the optical microscope and SPM observation with small SPM having resolution higher than that of the optical microscope can be realized in one compound microscope.
In the case where the optical microscope is separated from SPM, it is necessary that the observation is performed by exchanging the sample between the optical microscope and SPM. On the contrary, in the compound microscope, the observation can be performed without exchanging the sample.
In Jpn. Pat. Appln. KOKAI Publication No. 8-226928, a target observation region in the sample is set by the objective lens attached to the revolver, and the cantilever is positioned at a center portion of an objective lens visual field while the cantilever of the SPM unit is observed through the objective lens. Further, the objective lens is switched to the SPM unit by rotating action of the revolver to obtain an SPM image near the target observation region with the SPM unit. According to Jpn. Pat. Appln. KOKAI Publication No. 8-226928, it is easy to position the target observation region and the cantilever of the SPM unit, and observer's usability is improved during the observation.
In Japanese Patent No. 2824463, in order to enhance correspondence between an observation visual field position of the objective lens and an SPM image obtaining position, a relationship between visual field positions is previously stored from the optical observation image obtained with the optical microscope and the SPM image obtained with the SPM unit. Further, in the case where the optical microscope is switched to the SPM unit after the observation with the optical microscope, offset movement of the sample is accomplished by the amount of position shift between the optical observation image and the SPM image. According to Japanese Patent No. 2824463, when the optical microscope is switched to the SPM unit, it is possible that the SPM unit observation position is caused to correspond to the optical microscope observation position.